Radiology of the Oesophagus

Plain Radiography

• Reveals little useful information regarding the oesophagus except in the context of foreign body ingestion
• Foreign bodies tend to lodge at one of the following oesophageal constriction points:
  • Cricopharyngeus
  • Aortic arch
  • Left main bronchus
  • Diaphragmatic hiatus

Ultrasound

• Most of the oesophagus is inaccessible to conventional ultrasound examination
• The short cervical and abdominal segments are amenable to imaging in this way, but this is rarely used in clinical practice

Fluoroscopy

• Performed for a wide variety of indications
• Double-contrast images should be obtained using an effervescent agent, usually with the patient in the erect position
• Water-soluble contrast medium is used when a tear, perforation, or anastomotic leak is suspected

Endoscopy

• Oesophagogastroduodenoscopy (OGD/endoscopy) is the initial investigation of choice for most indications, particularly dysphagia
• Permits direct visualisation of the mucosa and biopsies can be taken
• Therapeutic manoeuvres that can be carried out endoscopically include:
  • Treatment of upper gastrointestinal (GI) haemorrhage
  • Balloon dilatation and/or stenting of strictures
  • Radiofrequency ablation (RFA) of dysplastic epithelium
  • Injection of botulinum toxin for motility disorders

Computed Tomography (CT)

• Most widely used in the staging of oesophageal cancer
• A CT of the thorax, abdomen, and pelvis should be acquired
• Good oesophageal and gastric distension is important:
  • The patient should be given 1-1.5 L of water to drink as well as effervescent granules
  • Should be imaged in the prone position
  • Intravenous contrast medium should be used whenever possible
  • The upper abdomen should be imaged in both the arterial and portal venous phases

Magnetic Resonance Imaging (MRI)

• Not used for imaging the oesophagus due to motion artefacts from cardiac motion, breathing, and peristalsis
• Whole-body MRI is under evaluation as an alternative to PET-CT for the staging of metastatic disease in oesophageal cancer

Endoscopic Ultrasound (EUS)

• Used to characterise abnormalities identified using other imaging techniques, in particular the staging of oesophageal cancer
• Less frequently used for the assessment of submucosal lesions of the oesophagus
• Enables the delineation of five layers of the oesophageal wall:
  • Mucosa
  • Submucosa
  • Muscularis propria
  • Muscularis mucosa
  • Adventitia
• Enables the sampling of structures deep to the oesophageal mucosa, particularly thoracic and upper abdominal lymph nodes

Radionuclide Radiology including Positron-Emission Tomography-Computed Tomography (PET-CT)

• For patients with oesophageal cancer, 18F-fluorodeoxyglucose (FDG) PET-CT is now the standard of care if radical treatment is intended
• Technetium-based radionuclide imaging of the oesophagus can be used for the identification of oesophageal motility disorders and gastrooesophageal reflux disease (GORD)

Pathological Features

Oesophageal Cancer

• Oesophageal cancer is the sixth most common cause of death from cancer in the United Kingdom
• There are two major histological types:
  • Squamous cell carcinoma
  • Adenocarcinoma
• Accurate preoperative staging of oesophageal cancer is difficult due to:
  1. The mobility of the oesophagus
  2. Its proximity to other organs making the assessment of local invasion problematic
  3. Malignant lymph nodes are usually not enlarged and may first arise some distance from the tumour
  4. Furthermore, unsuspected metastases may be present in up to 30% of patients at diagnosis

CT for Oesophageal Cancer

• The normal oesophagus when adequately distended should have a wall thickness of less than 5 mm on CT
• Tumours are seen as regions of wall thickening, which may be circumferential or asymmetric
• CT is limited in the local staging of oesophageal tumours because it is unable to delineate the layers of the oesophageal wall
• For nodal staging of oesophageal cancer, CT is relatively insensitive, as the majority of involved nodes are not enlarged

EUS for Oesophageal Cancer

• Superior to CT and PET-CT for T staging
• The sensitivity and specificity for identifying the various T stages of oesophageal cancer is high
• In some patients with advanced tumours, the stricture is too tight to permit passage of the standard radial echoendoscope
• An endobronchial ultrasound (EBUS) scope can be used in most of these cases if required
• For nodal disease, EUS has a sensitivity higher than that of PET-CT or CT, but it is less specific

PET-CT for Oesophageal Cancer

• In T1 tumours of the oesophagus, it is usually not possible to identify the tumour with PET, which should therefore be omitted if this stage is suspected endoscopically
• If a tumour is not detectable by PET-CT, it will be T2 or less in 70% of cases
• PET-CT otherwise suffers the same limitations as CT in terms of depth of mural invasion; EUS is therefore the preferred technique for T staging
• PET-CT is the technique of choice for identifying metastases to non-regional lymph nodes and other tissues such as the liver and skeletal muscle

Treatment of Oesophageal Cancer

• Involves a broad range of interventions that are dependent on:
  • The stage of tumour
  • Type of tumour
  • Fitness of the patient and local availability
• Options include:
  1. EMR (endoscopic mucosal resection)
  2. Oesophagectomy
  3. Palliative treatment
• Manoeuvres for maintaining oesophageal patency, most commonly stenting
• Palliative chemotherapy is used in patients with a good performance status
• Radiotherapy has an important role, particularly for the more radiosensitive squamous cell carcinoma
• The oesophagus is almost always substituted with a gastric conduit
• Both fluoroscopy and CT play an important role in the detection of postoperative complications